The 'this' context of type 'EventEmitter' is not assignable to method's 'this' of type 'Observable'.\n Types of property 'lift' are incompatible.\n Type '(operator: Operator) => Observable' is not assignable to type '(operator: Operator) => Observable'.\n Type 'Observable' is not assignable to type 'Observable'.\n Type 'string' is not assignable to type 'R'.